The compound ethylene (C2H4) is represented by this diagram. Two C's connected by two lines. Each C is connected by single lines to 2 H's. What statement best describes the arrangement of the atoms in an ethylene molecule? Each carbon atom shares two electrons with one hydrogen atom and also shares two electrons with the other carbon atom. Each carbon atom shares four electrons with one hydrogen atom and also shares four electrons with the other carbon atom. One electron is shared between each hydrogen atom and the carbon atom bonded to it, and two electrons are shared between the carbon atoms. Two electrons are shared between each hydrogen atom and the carbon atom bonded to it, and four electrons are shared between the carbon atoms.

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol